Synthetic multi-core ropes are used in a wide variety of fields, but are being increasingly used in the oil and gas industries, due to their strength and versatility. Amongst other tethering applications, multi-core ropes are used in the oil and gas industries to moor offshore facilities and anchor lines to the sea bed.
Multi-core ropes can be made to withstand very heavy loads before breaking, in some cases supporting many thousands of tonnes. The strength of a multi-core rope is derived from its composition, typically being made up of many smaller fibre ropes, known as sub-ropes, that are bundled together so as to run parallel to one another along the length of the rope. Although multi-core ropes are capable of withstanding high loads, their maximum load strength is determined by their weakest point, which is often a termination or connection point. Indeed, in most applications it is essential that a termination and/or connection be employed at some point along the length of the rope for the rope to be of use.
A rope termination for terminating a yarn rope is described in U.S. Pat. No. 3,932,697 (Hood) which comprises a frusto-conical body having a tapered peripheral surface and an axial bore. The rope yarns are inserted into the bore at the narrow end of the fitting and divided into two pairs of bundles with each pair being splayed diametrically outwards and returning along the outside of the fitting. The bundles are wrapped helically in opposite directions about the periphery of the main section of the rope for a predetermined distance and secured by means of tape or twine lashing wrapped several times around the ends of the bundles. When tension is applied downwardly to the rope (or upwardly to the fitting), the wrapped bundles cooperate to grip the periphery of the rope to fasten the fitting thereto. The Hood termination is specifically suited to providing a termination point for yarn fibres in a rope where it is desirable to separate the outer fibres from an inner core (such as an electrical cable). Although the Hood termination meets this need, it would not be suitable for providing a termination of a multi-core synthetic rope that would be able to withstand the typical loads encountered in the oil and gas industries.
Another termination is described in WO-A-2005/054710 (Marlow Ropes Limited). The Marlow document describes a termination for use with marine ropes where individual sub-ropes of a rope are spliced onto themselves forming connecting eyes. The sub-ropes are of varying lengths and their connecting eyes are each arranged onto individual load pins that extend between load plates. The load pins are arranged in a staggered arrangement in two rows with respect to the load plates to keep the transverse dimension of the termination relatively compact. The rope termination is arranged such that the load is transmitted from the rope into the plates through the individual load pins. As shown in FIG. 5 of the Marlow document, two such ropes may be connected to one another by a single load plate with load pins.
U.S. Pat. No. 5,539,960 (Vanasse) discloses a termination for an aramid fibre rope/cable. The termination comprises a threaded coupling provided with an internal sleeve through which the fibres are threaded. However, the fibres are exposed to the environment and are not protected. Also, while the ends of the sleeve over which the fibres are bent are curved, nevertheless, the fibres are distorted at both ends of the sleeve.
It is an object of the present invention to provide an improved termination for a multi-core rope, wherein the sub-ropes are arranged so that the termination can withstand high tensile forces when compared with prior art terminations. It is a further object of the present invention to provide a termination that can be quickly and easily connected to other terminations or fixtures. It is also an object to provide a termination that offers some protection for the sub-ropes and a mechanically advantageous connection between load pins supporting the sub-ropes and a coupling member of the termination